When four prima donna actors make a Vietnamese film (a “Platoon” parody) that goes haywire (it’s a movie inside a movie) it becomes the wildest and funniest movie of the year.  Robert Downey Jr. (hot off of “Ironman”) stars as Kirk Lazarus, an Aussie actor, so-into-his-Method-acting performance, that he dyes his skin black to play the African American Sergeant who’s part “Superfly” and part “James Brown.”  This is Downey Jr’s year and he should never play white again. There can’t be a movie fan of “Chaplin” or “Only You” – or you pick from his resume – that isn’t happy he’s back on track!  Jack Black plays a junkie comedian known for his fat flatulence flicks, while Ben Stiller is the ‘action’ star of the film and Hollywood’s biggest grossing actor on a downslide in his career, so this film has to make or break him. Put these goofballs together in a jungle, and the movie lets loose. Matthew McConaughey plays Stiller’s agent, Tom Cruise portrays an unrecognizable executive producer donning a fat suit and bald cap, hilarious to watch and obscene to listen to. Nick Nolte is the psycho dude who supposedly wrote the memoirs of “Tropic Thunder” of which the movie is based, while Steve Coogan is the film director of the movie within a movie, who sends his actors into their doomed territory – a heroine cartel – in hopes of saving his overbudget film (think “Survivor” and no cell phones).  The film’s real director is Ben Stiller, who hasn’t helmed a flick since “Zoolander’ in 2001 and “The Cable Guy” in 1996. Given all the recent strikes, bargains, and negotiations of real life writers and actors, not to mention what it takes to bring a film in under budget these days, the brilliant “Tropic Thunder” is undoubtedly a big F.U. to the studio system of Hollywood.   Four tiaras through the roof!